Grinding machine



May 15, 1934. E STUBBS 1,958,551

GRINDING MACHINE Filed May 19. 1932 5 Sheets-Sheet l w @MKM Filed May 19, 1932 5 Sheets-Sheet 2 ZZ jme/nto@ E VERARD S TUB B5 May 15, 1934. E. sTuBBs GRINDING MACHINE Filed May 19. 1952 5 Sheets-Sheet 4 gmmtou EVERAHD STL/556 W/TNESSES MA K. owew.

May 15, 1934. E, STUBBS 1,958,551

GRINDING MACHINE 4Filed May 19, 1932 5 Sheets-Sheet 5 F/G.6v

Jvwmto/o EVE/5A RD @TUBES l/l//T/vEssES JLM/,M6 m1 M5 QQ um? Patented May 15, 1934 PATENT OFFICE l GRINDING MACHINE Everara Stubbs, springfield, vt., assignor a Norton Company, Worcester, Mass., a corporation of Massachusetts Application May 19, 1932, Serial N0. 612,233

` 16 Claims.

This invention relates to grinding machines and more particularly to machines adapted to grind work pieces of irregular contour.

Heretofore in the grinding machines utilized to produce non-circular shapes, such as cams, it has been the practice to employ a. grinding wheel of a cylindrical shape; and in order that the periphery of the wheel may engage vthe work throughout the entire surface as it rotates, the

Work head support has been arranged to move back and forth towards the center of the grinding wheel as the work rotates. vSuch machines are unsatisfactory due to their complicated construction necessitating a complex movement l5 through which the work must be cyclically moved during the grinding operation, as well as to the' fact that the grinding wheel may be used only within certain narrow limits of diameter if satisfactory grinding results are to be obtained. Great difllculty has been encountered in producing certain types of non-circular work, such as the familiar types of spline shafts by employing mechanisms asheretofore proposed.

As result of my experimentation, I have found it practicable to grind work pieces of irregular contour by a method which does not require any relative oscillation lbetween the work and the wheel, but which depends on specially shaping the grinding wheels and rotating the wheel and 3o work in synchronismat such angular rates during grinding that the wheel and work remain in proper grinding phase relation at all times;

i It is the primary object of my invention to provide such a grinding machine in which the grinding wheel is of irregular contour and in which it may be readily trued to the desired shape and cutting condition so that work piecesof various contours may be correctly and eillciently ground.

A further object is to provide a truing mechanism which will pre-shape the grinding wheel to the exact contour required for grinding a work piece of irregular or eccentrically mounted cylindrical contour, and in particular to coordinate the parts of such a truing mechanism with the grinding wheel and work rotating mechanism that thewheel may be readily trued without removal from the machine.

showing the drive for the wheel and the work;

Fig. 2 is a fragmentary view showing-the relation of the grinding wheel, work blank and forming attachment for truing the wheel; y

Fig. 3 is a fragmentary view showing the mecha- 69 nism for forming or truing the wheel;

Fig. 4 is a fragmentary cross sectional view of the forming mechanism taken approximately von line 4 4 of Fig. 3;

Fig. 5 is a sectional View taken along line 5-5136 of Fig. 1 showing this invention as adapted for grinding a plurality of work blanks simultaneously; and

Fig. 6 is a diagrammatic View showing the relation of the wheel and the work in various angular positions during the grinding operation.

In accordance with my invention, I have provided a grinding machine wherein the grinding wheel is given a particular shape that is the conjugate of the desired work contour, such as. a cam or an eccentrically mounted cylindrical work piece. The wheel andthe work are-rotated in a definite angular timed relation, but at different linear speeds at the point of grinding contact so that a given portion o f thewheelwill always s0 contact with a given portion of thework. In other words, a grinding wheel is conjugate to an irregular work piece in the sense of this invention when the cutting portion of the Wheel pro-' jects or recedes in complement tothe receding 35' or projecting parts of the work with whichsaid cutting parts contact and the wheel and work rotate in substantially continuous contact but at different linear speeds. In a machine of this type, certain xed points in the work and the wheel are withheld from recession or movement towards or from the work axis during thegrinding operation, .the `only movement thereof being the feeding action required to grind\ the work to the desired extent.. In other" words, if the 95 operative faces of 'the grinding wheel and thework aretheir peripheries, then their axesare fixed and the sum of the radii of the work and the wheel at the point of. grinding contact always remains constant except as the grinding wheel is 100.

fed toward the work axis to reduce the work to the required size. If the side face of either wheel or work is utilized, then one may consider a fixed plane therein perpendicular .to the axis of .rota-'- tion as the position from which'measurement is 105 made.

Oneform of my machine which embodies this principle, has the grinding wheel and the work arranged torotate in angular synchronism about relatively fixed parallel axes with their periphl Y eries in operative contact, the wheel and work being relatively movable towards each other so that the wheel 'may be fed into the work to grind f it to the desired size. It should be noted, however, that the shape or contour of the work is controlled wholly by the shape of the grinding l.wheel and'not by the infeed thereof, as is the case .in the standard type of cam grinding machine the truing tool movement is rotated in angular.

synchronism lwith the wheel. If a long piece of work is to be ground, the work and the grinding wheel may be axially reciprocated relative to each other by any standard reciprocating mechanism so that the wheel may be traversed throughout` the length of the work while the irregularly shaped non-cylindrical surface of the grinding wheel and the work remain in operative Contact,`v

as is common practice in cylindrical grinding'. A suitable cross feed mechanism may be employed to vfeed the grinding wheel towards the work as it wears away and to reduce the work to a predeterm'ined size. It is to be understood, however, that the work and wheel axes are substantially immovable vand they are not` oscillated towards and from eachother during the grinding operation. Hence, the only movement of these sub stantially fixed axes is the small relative feeding` movement between the wheel and the work required to reduce the workin size.

'v One embodiment of my invention, as illustrated in' the `drawings,comprises a machine base carrying vavgrinding wheel 11 mounted on a `rotatable spindle `12 which in turn is supported on a wheel slide 13.` The. workfblank 15,-which-is a special type of-splined shaftor'integral key shaft covered by my co-pending application, Serial 215,983, filed August 27, 1927",wis` rotatably mounted between a headstock 16A and footstock'l'? which are in turn 1. supported on the work table 18'.y The axes of the grindingf'wheel and the work are fixed relative toeach 'otherduring the vgrinding operation except for -the Arelative `feeding of the work and grinding Wheel to reduce the work to the requiredV .size y Aswillustratedv the drawings, a cross-feed mechanism is provided to move the fwheel slide and 'grinding'wheel towardsand from-the lwork f to reduce the same to apredeterminedlsize.v f This mechanism may -be ofA any suitablelconstruction such as that' shown inthe patent to Wilcox No.1'

1,197,700 offSeptember-12,4916, to which "referencemay be-hadfor a detailed disclosure thereof..y This wheel feeding mechanism comprising -a half lnut 12o-mounted on thevunde'rside of the wheelwslidey 13y and adapted tto engage the feed screw` 2'1` `which isrotatably mounted in suitable bearings'in a base 22. The oiiterend offthe feed screw is'provided with al gear 23 engaging a pinion 24 which is operatively connected to a hand wheel 25. By turning the hand wheel 25 a rotary movement is transmitted through gears'- 24 and k23 to screw 21 which, operating through the half nut- 20,'moves'the grindingwheel slide and'thereby f causesfa relative feeding movementbetween the.v

grinding wheel and the work. This feeding movement is utilized only to compensate for wheel wear or to feed 'the wheel to reduce'the work to the required dimension.

It is essential that the rotation or the grinding wheel and the work be angularly synchronized so that the specially shaped'operating face of the grinding wheel will produce a'conjugate surface on the work. r

To rotate these parts, 4a motor 27 is mounted either adjacent to the machine as shown in Fig. 1 or on or within the base 22. This motor drives a cross shaft 28 by means of a belt 29 passing over the motor pulley 30 and over the wide driven vpulley or drum 31 fixed on the outer end of shaft 28which serves to impart a synchronous rotation tothe wheeland work. The shaft 28 is mounted in suitable bearings 32 and 33 on; the wheel slide 13 and held in position by collar 34 and worm 35 engaging the ends of the bearings, whereby it is` means of a key 39 and maintained in 'fixed driving relation with aA worm gear 40 on the work driving spindle 41 which is mounted in the headstock. A yoked bearing support comprising spaced bearings 42 rotatably engaging yshaft 28 and mounted on opposite sides of the worm 38, together with a head 43 connected by arms 44 'to the bearings 42 is rotatably suspended from the work driving'spindle 41. This construction serves to permit the grinding wheel to be moved'towards and from the work without changing -the angular relationof thewheel and the work, since the forward vor rearwardy axial movement of shaft 28 is not imparted to worm 38 slidably keyed to the drive shaft 28. It will be readily seen from this construction that anyrotation of the shaft 28 will be transmitted to rotate the grinding wheel and the work in synchronism.

vAs illustrated in the drawings, I have provided atriple worm 35 to engage the worm wheel- 36 on the grinding wheel'spindle 12 while on the other' end of the shaft 28 the worm 38 is of the single thread type. By utilizing this arrangement, the grinding wheel will berotated three times for each rotation'of the work with the wheel and work both rotated in the'samel angular 'directionas shown in Fig. 6. ThisA ratio .if rotation of the 'grinding wheel andlwork is" applicable only for grinding abody-s'uch asjthe cam illustrated' in the drawings, in whichthe three lobes of the'cam'aresymmetrical.v In the caseofthe ordinary camshaft, such as used in internal-'coinbustion engines, it is necessary to. employ a l to 1 ratio, wherein both the wheel andtheworkare rotatedv synchronously at'the same angular rate. Ifl desired, the wheel and thel work may be' rotated in opposite angular directions, so that their adjacent faces at point of grinding contact will iso holder 47 which is slidably mounted in a vertical slide 48, as shown in Fig. 4. To shape the face of the grinding wheel so that it will produce a conjugate surface on the work of the desired size and shape, a master form or cam 49 is rotatably mounted on the slide 48 as illustrated. The rotation of the master form 49 will be transmitted to cause a movement of the truing tool 46 toward and from the surface of the grinding wheel. A spring pressed plunger 50 actuated by a spring 51 is provided to maintain the follower 52 in operative engagement with the master cam 49. A stud 53 threaded into the slide member 48 rides in a slot in the holder 47 and serves to prevent angular movement of the diamond holder.

It is essential that the master cam 49 be rotated in angular synchronism with the work spindle. As illustrated in the drawings, a spiral gear 54 is fixed on the work driving spindle and meshes with a spiral gear 55 on the lower end of a shaft 56 which is provided with a suitable bearing 57 secured on the headstock 1'6 by arm 58. A telescopic shaft 59 is connected with shafts 56 and 60 through universal joints .62 which permit the shafts to be out of alignment .as the diamond is traversed across the face of the Wheel and fed into the Wheel as itis 'reduced in size. The shaft 60 is supported in a bearing 63 fixed on the slide 48 and has at its upper end a spiral gear meshing with a spiral gear 67 lsecured on the end of the master cam shaft 68.

It will thus be seen that any rotation of the headstock spindle 41' will be transmitted to produce a corresponding rotation of the master form 49 which in turn transmits a movement to the diamond or truing tool 46 towards or fromthe periphery of the grinding wheel, thereby producing a surface on the grinding wheel which is the conjugate of the master cam. In the present instance,l the master cam 49 as shown in the drawings is of identical size and shape as the final required work size and is, therefore, rotated in synchronism with the work piece 15 at the same angular rate. It is to be understood that other shapes of master cams and other constructional arrangements may be employed, but the master cam must be rotated in synchronism with the work spindle and it must be of such form as to cause the truing tool to shape the grinding wheel the exact conjugate of the flnal desired work shape.

In order that the diamond may. be fed towards the periphery of the wheel as the wheel wears away, the truing tool is mounted on`a vertical slide 48 which is slidably mounted on a horizontal slide member 70, so that the tool may be moved vertically towards and from theV periphery of the wheel. As illustrated in the drawings, a nut and screw mechanism is-provided to produce the desired adjustment of the vertical slide. This preferably comprises a screw 71 rotatably fixed in a suitable bearing 72 in the member 70 and threaded into a projection 74 of the vertical slide 48. 'Ihe upper end of screw 71 is fixed to a hand wheel 75 so that it may be readily turned to position the truing tool 46 relative to the periphery of the wheel. In order that the truing tool 46 maybe traversed across the face of the wheel, any suitable mechanism may be provided, such as a cross slide 77 adapted to mate with a dove tailed sliding surface on themember 70 and positioned so that the sliding movement is parallel with the grinding wheyel axis. A .screw 80 is mounted in suitable bearings (not shown) in the cross slide 77 of the truing mechanism engaging a rrnut or suitable projection 8l of the member 70 so that any rotation of the screw 80 will be transmitted to traverse the truing tool 46 across the face of the grinding wheel parallel to its axis. The screw 80 is provided with a hand whee182 so that the screw may be readily turned to produce the desired traversing action of the truing4 tool across the work.

As illustrated in Fig. 5, a modification of this invention has been illustrated whereby the wheel spindle 12 suitably mounted on the slide 13' may carry a plurality of grinding wheels 1l' in spaced relation and arranged thereon to correspond with the positioning of cam blanks 15' on an automotive camshaft or the like. By employing a construction of this type, a plurality of cams or irregularly shaped objects on the same shaft may be simultaneously ground. The various constructional features on a machine utilizing more than one wheel are in general the same as above described, but will'be duplicated as required for the grinding operation and for truing each wheel. The camshaft to be ground is rotated through the work drive spindle 41 and synchronized with the wheels by means of the drive shaft 28, which connects them as above described. Likewise the gear 54 driven with the work serves to rotate the shaft 56 and thus rotate the master camshaft 68 in synchronism with the work and the wheels, whereby the latter may be properly trued. It will be readily seen from this construction that the grinding wheels will not only be formed as the conjugates of the respective cams on a shaft, but they will be trued so as to produce the correct grinding of the various cams on the work piece to be finished yirrespective of the shapes and the angular positions of each cam on nthe shaft.

- y In the operation of my machine a master form or cam of the required shape is mounted in, operative relation with the truing mechanism. The grinding wheel of suitable characteristics is then set in rotation and the hand wheel 75 is turned to feed the diamond truing tool 46 into operative relation with the face of the grinding'wheel 11. The hand wheel 82 is thenturned to traverse the diamond across the face of thev wheel after which the hand wheel 75 is turned to produce a further feeding of the diamond into the face of the wheel. This operation is continued until the grinding wheel has been trued so that its shape is the conjugate of the master form or template, thereby forming the grinding wheel as the conjugate of the required work shape. During the truing operation, the rotation of the grinding wheel and the master cam 49 in angular synchronism causes the truing tool 46 to move towards and from the wheel axis in a definite phase relationwith the wheel rotation in order to true the wheel face to the desired contour. The work blank is then mounted on centers between the headstock 16 and footstock 17. After the work and wheel have been angularly located and put into synchronous rotation, the grindingwheel is fed forward by turning the` hand wheel 25, which in turn serves to rotate the feed screw 21, thereby transmitting a feeding movement to the slide 13. The work blankl will be rotated in synchronism with the grinding wheel so that any high spot on the wheel will produce correspondinglylow spots onv the work and vice versa as shown diagrammatically 1ST:

It is to be understood that the term "conjugate as used in this specification and in the claims is associated with those curves which are so related as to be produced by the rotation of the connecting surfaces of the tool and the work about fixed axes with their angular velocities equal or in a simple ratio, where these surfaces are` in part irregular in shape and their peripheries are 'of unequal extent. 'If the work and the wheel were rotated in opposite directions and their circumferences were the same in lengthand their angular velocities were the same, the two surfaces would have a pure rolling contact; but with thedissimilarity of length of the two peripheries a slipping or cutting action between the wheel and the work serves to grind the latter to size. If the wheel and the workV rotate in the same direction, the cutting conditions are the same as in a normal Acylindrical grinding operation. They may be rotated in vopposite directions, if desired. It is y on the work.

It is to be understood that the present invention applies to forming eccentrically revolved cylindrical surfaces, such as crank pins, as well as noncircular peripheral surfaces, the cross section or contour of which do not form geometric circles, such as cams, and to the forming of irregular surface contours on the side faces of rotary bodies. In each case, the line of grinding contact between the wheel and work is ata varying distance from the axis of rotation of the grinding wheel, or in other words the line of grinding contact moves towards and from the axis of wheel rotation during the grinding operation. For example, a wheel employed for grinding a crankpin may be circular in shape but eccentrically mounted relative to its geometric center. The work and the wheel are said to be in angular synchronism when their angular velocities are in simple ratios of one to one, two to one, three to oneandpso forth. Similarly, the master form and the truing tool move in cyclic synchronism or phase relation with each rotation lof the wheel, in that the master form or the tool moves always in the same definite path for each rotation of the wheel through the same angular distance, and the cycle is repeated either once or a multiple number of times for each full rotation of the wheel. In

4other words, wheel and work are always rotated through a proportionate angular displacement.

This application of conjugate grinding or forming of a work piece has been illustrated. as applicable to grinding the outer surface of a body, but this invention is not limited to this application. It is equally applicable to grinding holes of an irregular shape by forming the grinding wheel so that when it rotates in synchronism with the work blank, it will produce a conjugate surfaceon the inner periphery of the work aperture. These principles apply to various types of grinding machines, in which the wheel grinds on its .peripheral or on its side face, and they apply also to the production of many different shapes of work. Various other applications of this invention are clearly within the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. A grinding machine comprising a grinding wheel, a truing vtool movable laterally and toward and from the wheel, means to traverse the truing tool across the operative face of the wheel, a rotary master form connected to move the truing tool towards and from the wheel face and means to rotate the master form in synchronism with the grinding wheel so that the conjugate of the master form will be produced on the grinding wheel.

2. A truing apparatus for grinding machines comprising a wheel slide, a grinding wheel thereon, a truing tool holder mounted on said slide for movement laterally thereof and towards and from the wheel, means to traverse said tool across the face of the wheel, a rotatable master form connected to move the truing tool towards and from the grinding wheel and means to synchronize the rotation of the grinding wheel and the master form so that the conjugate of the form will be4 generated on the grinding wheel.

3. A wheel truing mechanism foroperation on a surface of a rotating lwheel including a support, a truing member mounted on the support for movement in a direction transversely of the wheel surface to be formed and for movement in a direction toward and from the surface to be formed, means for effecting a traversing movement of the truing mechanism with respect to said surface, and additional means for automatically effecting a cyclic movement of the truing mechanism toward and from said surface for each rotation thereof.

4. A mechanism for producing an eccentric surface on the periphery of a rotatable wheel including a support in fixed relation to the axis of rotation of the wheel, a truing member mounted on the support for movement in a direction toward and from the periphery of the wheel, a contour determining member rotatable in synchronism with the wheel, and connections between the truing device and contour member determining the movement of the truing member toward and from the periphery of the wheel on joint rotation of the wheel and contour member.

5. A mechanism for producing an eccentric surface on the periphery of a rotatable wheel including a support in fixed relation to the axis of rotation of the. wheel, a truing member mounted on the support for movement in a direction toward and from the periphery of the wheel, a contour determining member rotatable in synchronism with the wheel, connections between the truing device and contour member determining the movement of the truing member toward and from the periphery of the wheel on joint rotationl of the wheel and contour member, and means for effecting a relative transverse shifting movement of the wheeland truing member in a direction axially of the wheel, whereby the truing member will engage all points of the desired zone transversely of the wheel in a relation to the axis thereof determined by the meansl for controlling the movement of the truing member toward and from the wheel surface.

6. A mechanism for producing an eccentric surface on the periphery of a rotatable wheel including a support in fixed relation to the axis of rotation of the wheel, a truing member mounted on.

the support for movement in a direction towards and from the periphery of the wheel, a contour determining member rotatable in -synchronism with the wheel, connections between the truing device and contour memberdetermining the movement of the truing member towards and from the periphery of the wheel on jointl rotation of the wheel and contour member, means for effecting a relative transverse shifting movement of the wheel and truing member in a direction axially of the wheel, whereby the truing member will engage all points of the desired zone transversely on the wheel in a relation to the axis thereof determined by the means for controlling the movement of the truing member towards and from the wheel surface, and additional means for effecting a manual adjustment of the truing member in a direction towards and from the wheel surface.

7. A grinding machine having a base, a rotatable grinding wheel of non-circular contour mounted thereon, a truing apparatus having a tool arranged to move towards and from the wheel axis and to traverse across the face of the wheel, and a master form rotated in synchronism with the wheel which is connected to actuate the truing tool and produce a wheel yface shaped as the conjugate of the master form. v-

8. A grinding machine comprising a grinding wheel of a non-circular contour adapted to grind a conjugate non-circular work shape, a truing tool, a support for moving the tool towards and from the wheel axis to true said wheel contour, a master form connected to control the truing movement of the tool which has a predetermined contour related to that of the finished work and means for moving the master form in cyclic synchronism with each grinding wheel rotation during the truing operation, whereby the wheel is trued to a contour of non-circular section which is the conjugate of the finished work shape.

9. A grinding machine, having a base, an axially fixed rotatable grinding wheel having a cutting face shaped to a contour which is coniugate to the desired shape of the finished work, means to rotate the wheel and work in abrading engagement on substantially fixed axes and in angular synchronism to produce the desired work shape, and truing mechanism, including a truing tool and means for moving the tool which is operated in synchronism with the work rotation for shaping the wheel face to be the conjugate of the desired work shape. Y

10. A machine adapted for grinding a surface of irregular contour comprising a grinding wheely having a contour which is the conjugate of that of the finished work, and a rotatable worksupport, means to rotate the work and wheel in angular synchronism while their surfaces are in engagement and their axes are in a non-oscillative relation to produce the desired work shape, and a truing mechanism, including a master cam rotated in synchronism with the work rotation, for shaping the wheel periphery as the coniugate of the desired work contour.

11. A grinding machine comprising a grinding wheel having its line of contact with the work piece at a varying distance from the axis of wheel rotation, a tool support, a truing member mounted on the support for movement towards and wheel periphery and for movement totwards and f from the wheel axis, means for effecting a transverse movement of the truing member with respect to the wheel periphery, and means for effecting a movement of the truing member towards and from said wheel axis in cyclic phase relation to each wheel rotation so as to` true said wheel face to the desired contour.

13. A grinding machine comprising a grinding wheel having the line of grinding contact at a varying distance from its axis of rotation, a truing tool, a support for the tool including a rotatablemaster form arranged to' move the tool towards and from the wheel, and means to rotate the master form and grinding wheel in angular l 14. A grinding machine comprising a wheel slide, a grinding wheel thereon having its line of grinding contact at a varying ,distance from the axis of wheel rotation, a truing tool holder mounted on said slide for movement laterally thereof and towards and from the grindingwheel, means to traverse the tool across the face of the wheel, means including a rotatablefmaster form having a curved operative face which is at a varying distance from' its axis of rotation and arranged to cyclically move the truing tool towards and from the grinding wheel during each wheel rotation, and means to synchronize the rotation of the grinding wheel and the master form so that the wheel will .be shaped to a predetermined contour.

15. A grinding machine comprising a grinding wheel, having its line of 'grinding contact at a varying distance from the axis of Wheel rotation, a support mounted in fixed relation tothe axis of rotation of the grinding wheel, a truing tool mounted on the support for movement in a direction towards and from the wheel axis, a master form rotatable in. angular cyclicsynchronism with the grinding wheel, connections between the truing tool and master form determining the movement of the truing tool towards and from the wheel axis, and means to feed the master form towards the wheel axis and compensate for wheel wear without affecting its angular relation therewith, whereby the truing tool may be maintained in engagement with the grinding wheel as it is reduced in size and serve to shape it to a predetermined contour.

16. A grinding machine comprising a grinding wheel having its line of grinding contact at a varying distance from the axis of wheelrotation, a truing tool therefor, means for traversing the tool transversely across the wheel face, mechanism including a rotatable master form to move the truing tool towards and from the wheel axis during the truing operation, positive driving connections between the wheel and master form arranged to rotate the master form in cyclicA synchronism with the wheel rotation whereby thel truing tool may be caused to move in timed relation to thel wheel rotation and shape the grinding wheel to a predetermined contour,

and means to feed the master form towards thel grinding wheel to compensate for reduction in wheel size without disturbing the synchronism of the master form and grinding wheel. l

EVERARD STUBBS. 

